Miniature pump for liquid cooling system

ABSTRACT

A miniature pump includes a pump casing ( 1 ) defining therein an inner space with an inlet ( 104 ) and an outlet ( 110 ) both being in flow communication with the inner space, a liquid circulating unit ( 2 ) having an impeller ( 26 ) received in the inner space, a motor driving unit ( 3 ) received in the inner space to drive the impeller to rotate, and a partition wall ( 14 ) arranged in the pump casing to space the liquid circulating unit and the motor driving unit. The impeller carries a first permanent magnet ( 260 ). The motor driving unit includes a motor having a rotor ( 34 ) and a second permanent magnet ( 340 ) attached to the rotor. The second permanent magnet corresponds to the first permanent magnet with a flux gap formed therebetween. Each of the first and second permanent magnets has a plurality of alternating N and S poles.

TECHNICAL FIELD

The present invention relates generally to pumps, and more particularly to a miniature pump for a liquid cooling system for cooling an electronic package.

BACKGROUND

With continuing development of the computer technology, electronic packages such as the CPUs are generating more and more heat that is required to be dissipated immediately. The conventional heat dissipating devices such as combined heat sinks and fans are not competent for dissipating so much heat any more. Liquid cooling systems have thus been increasingly used in computer technology to cool these electronic packages.

A typical liquid cooling system comprises a heat absorbing unit for absorbing heat from a heat source, and a heat dissipating unit which is filled with liquid. The liquid conducts heat exchange with the heat absorbing unit, thereby taking away the heat of the heat absorbing unit when the liquid is circulated. Typically, a miniature pump is used to circulate the liquid in the liquid cooling system.

The miniature pump comprises an impeller and a motor for driving the impeller to rotate so as to circulate the liquid. The motor used therein generally comprises a printed circuit board having a plurality of circuits to control the motor. In conventional use, the whole pump is disposed in the liquid such as water. The pump is possible to be damaged due to short circuit of the circuits of printed circuit board in the water. To overcome the shortcoming, special insulating design and manufacturing of the printed circuit board are necessary for preventing short circuit of the printed circuit board. However, besides getting an improved reliability, this insulating design and manufacturing inflate costs of the pump as well.

Therefore, a miniature pump with low cost and high reliability is desired.

SUMMARY OF THE INVENTION

The present invention is directed to a miniature pump with low cost and improved reliability.

A miniature pump in accordance with the present invention comprises a pump casing defining therein an inner space with an inlet and an outlet both being in flow communication with the inner space, a liquid circulating unit comprising an impeller received in the inner space, a motor driving unit received in the inner space to drive the impeller to rotate, and a partition wall arranged in the pump casing to space the liquid circulating unit and the motor driving unit. The impeller carries a first permanent magnet. The motor driving unit comprises a rotor and a second permanent magnet attached to the rotor. The second permanent magnet corresponds to the first permanent magnet with a flux gap formed therebetween. Each of the first and second permanent magnets has a plurality of alternating N and S poles.

Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of the preferred embodiments of the present invention with attached drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, isometric view of a miniature pump according to a preferred embodiment of the present invention;

FIG. 2 is an assembled view of the miniature pump of FIG. 1;

FIG. 3 is a cross sectional view of the miniature pump of FIG. 2, but viewed from another aspect; and

FIG. 4 is a cross sectional view of a miniature pump according to an alternative embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a miniature pump in accordance with a preferred embodiment of the present invention comprises a pump casing 1 having an inner space, and a liquid circulating unit 2 and a motor driving unit 3 received in the inner space of the pump casing 1.

The pump casing 1 comprises a hollow main body 11, a top cover 10 hermetically attached to a top end 101 of the main body 11, and a bottom cover 19 attached to a bottom end 102 of the main body 11. A sealing ring 108 is disposed between the main body 11 and the top cover 10 to prevent liquid leakage. The top cover 10 forms an annular groove 106 at a bottom edge thereof for receiving a sealing ring 108 therein. An inlet 104 is formed on the top cover 10 for allowing liquid to enter the pump casing 1. An outlet 110 is formed on the main body 11 for allowing the liquid to exit the pump casing 1.

The main body 11 transversely forms an inner partition wall 14. This partition wall 14 effectively divides the inner space of the main body 11 into a top space 15 and a bottom space 18.

Referring also to FIG. 3, a spacing plate 12 is transversely arranged in the main body 11. The spacing plate 12 further divides the top space 15 of the main body 11 into a first chamber 16 between the spacing plate 12 and the top cover 10, and a second chamber 17 between the partition wall 14 and the spacing plate 12. A positioning hole 120 is defined in the spacing plate 12 at a center portion thereof. A plurality of through openings 122 is defined in the spacing plate 12 adjacent the positioning hole 120 to make the first and second chambers 16, 17 intercommunicate.

The liquid circulating unit 2 is mounted in the second chamber 17 of the pump casing 1. The liquid circulating unit 2 comprises a shaft 20 mounted between the partition wall 14 and the spacing plate 12, a bearing 22 pivotably attached to the shaft 20 and an impeller 26 attached to the bearing 22. Alternatively, the bearing 22 may be integrated with the impeller 26. A first permanent magnet 260 is embedded in the impeller 26. The first permanent magnet 260 has a ring flat body magnetized as having a plurality of alternating N and S poles along the ring body. For positioning the shaft 20, the partition wall 14 forms a shaft support 140 having a blind hole (not labeled) receiving a bottom end of the shaft 20 therein, and a top end of the shaft 20 engages in the positioning hole 120 of the spacing plate 12. A pair of locking rings 24 is attached to the shaft 20 near opposite ends thereof respectively for limiting axial movement of the shaft 20.

The motor driving unit 3 is received in the bottom space of the pump casing 1. The motor driving unit 3 is positioned on the bottom cover 19 and comprises a motor having a rotor 34 and a printed circuit board 31 for controlling rotary of the rotor 34. A second permanent magnet 340 used as a magnetic member is attached to the rotor 34 for spinning therewith, corresponding to the first permanent magnet 260. Like the first permanent magnet 260, the second permanent magnet 340 also has a ring flat body magnetized as having a plurality of alternating N and S poles along the ring body. An axial flux gap is cooperatively created between the first and second permanent magnets 260, 340. The rotor 34 is covered with a layer of magnetically conductive material; therefore the second permanent magnet 340 is attached to the rotor 34 by magnetic attract force. Alternative means such as adhesive may be used to attach the second permanent magnet 340 to the rotor 34.

In operation, the rotor 34 of the motor of the motor driving unit 3 rotates to drive the second permanent magnet 340 to rotate therewith. The first permanent magnet 260 is driven to rotate with the second permanent magnet 340 by the attract force theretween. The impeller 26 thus rotates with the first permanent magnet 260 to circulate the liquid in the liquid cooling system.

In the present invention, the motor is completely isolated from the liquid by the partition wall 14. Short circuit of the circuits of the printed circuit board 31 due to the liquid will never occur. Therefore, no special insulating design is required any more. The pump of the present invention thus has a reduced cost and improved reliability.

Referring to FIG. 4, a miniature pump according to an alternative embodiment of the present invention is shown. Most parts of the miniature pump of the alternative embodiment are the same as the preferred embodiment. Main differences are that in the alternative embodiment the first and second permanent magnets 260′, 340′ are both cylindrical while in the preferred embodiment they are flat; a radial flux gap is thus formed between the first and second permanent magnets 260′, 340. Another difference is that the spacing plate 12′ downwardly forms a protrusion 120′ corresponding to the top end of the shaft 20′ for limiting axial movement of the shaft 20′.

It is understood that the invention may be embodied in other forms without departing from the spirit thereof The above-described examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given above. 

1. A miniature pump for use with a liquid cooling system comprising: a pump casing defining therein an inner space with an inlet and an outlet both being in flow communication with the inner space; a liquid circulating unit received in the inner space, the liquid circulating unit comprising an impeller being rotatable to drive the liquid to enter the inner space via the inlet and to exit the inner space via the outlet, a first permanent magnet being carried by the impeller; a motor driving unit received in the inner space to drive the impeller to rotate, the motor driving unit comprising a rotor and a second permanent magnet attached to the rotor, the second permanent corresponding to the first permanent magnet with a flux gap formed therebetween, each of the first and second permanent magnets having a plurality of alternating N and S poles; and a partition wall arranged in the pump casing to space the liquid circulating unit and the motor driving unit.
 2. The miniature pump as described in claim 1, wherein each of the first and second permanent magnets comprises a ring flat body, and an axial flux gap is created between the first and second permanent magnets.
 3. The miniature pump as described in claim 1, wherein each of the first and second permanent magnets comprises a cylindrical body, and a radial flux gap is created between the first and second permanent magnets.
 4. The miniature pump as described in claim 1, wherein the pump casing comprises a hollow main body and top and bottom covers attached to top and bottom ends of the main body respectively, and the partition wall is transversely formed in the pump casing to divide the inner space into a top space for receiving the liquid circulating unit and a bottom space for receiving the motor driving unit.
 5. The miniature pump as described in claim 4, wherein a sealing ring is arranged between the top cover and the main body to prevent leakage of the liquid.
 6. The miniature pump as described in claim 4, wherein the rotor is covered with a layer of magnetically conductive material, and the second permanent magnet is attached to the rotor by an attracting force.
 7. The miniature pump as described in claim 4, wherein the pump casing further comprises a spacing plate to divide the top space into a first chamber communicating with the inlet and a second chamber communicating with the outlet, and the first chamber is in communication with the second chamber.
 8. The miniature pump as described in claim 7, wherein the spacing plate defines a through opening corresponding to a center portion of the liquid circulating unit.
 9. The miniature pump as described in claim 7, wherein the liquid circulating unit comprises a shaft positioned by the spacing plate and the partition wall, and the impeller is rotatably attached to the shaft.
 10. The miniature pump as described in claim 9, wherein the partition wall forms a shaft support defining a blind hole receiving an end of the shaft, and the spacing plate defines a positioning hole at the center portion thereof receiving an opposite end of the shaft therein.
 11. The miniature pump as described in claim 10, wherein the liquid circulating unit comprises a pair of locking rings attached to the shaft near the opposite ends thereof.
 12. The miniature pump as described in claim 9, wherein the partition wall forms a shaft support defining a blind hole receiving an end of the shaft, and the spacing plate forms a protrusion corresponding to an opposite end of the shaft.
 13. The miniature pump as described in claim 1, wherein the first permanent magnet is embedded in the impeller.
 14. The miniature pump as described in claim 1, wherein the rotor is a rotor of an electrical motor.
 15. A miniature pump for use with a liquid cooling system, comprising: a pump casing comprising a partition wall transversely formed therein to define an inner space of the pump casing with isolated first and second spaces; an inlet and an outlet provided on the pump casing to communicate with the first space; a liquid circulating unit positioned in the first space, the liquid circulating unit comprising an impeller with a first permanent magnet carried thereon; a motor driving unit positioned in the second space, the motor driving unit comprising a motor and a second permanent magnet being drivable to rotate by the motor; wherein when being rotated by the motor, the second permanent magnet drives the first permanent magnet to rotate by magnetic force generated therebetween, whereby the impeller rotates to circulate liquid in the liquid cooling system.
 16. The miniature pump as described in claim 15, wherein the pump casing comprises a hollow main body, a top cover hermetically attached to one end of the main body to form the first space between the top cover and the partition wall, and a bottom cover attached to an opposite end of the main body to form the second space between the partition wall and the bottom cover.
 17. The miniature pump as described in claim 15, wherein the motor comprises a rotor covered with a layer of magnetically conductive material, and the second permanent magnet is attached to the rotor by an attracting force.
 18. The miniature pump as described in claim 15, wherein each of the first and second permanent magnets comprises a ring flat body, and an axial flux gap is created between the first and second permanent magnets.
 19. The miniature pump as described in claim 15, wherein each of the first and second permanent magnets comprises a cylindrical body, and a radial flux gap is created between the first and second permanent magnets.
 20. A liquid pump, comprising: a first space defined in said liquid pump, and a second space defined in said liquid pump and liquid-isolated from said first space by a partition wall; a liquid inlet and a liquid outlet defined in said liquid pump to communicate said first space with outside of said liquid pump; a magnetic impeller received in said first space and used to impel liquid in said first space; and a driving unit received in said second space, comprising a motor and a motor-drivable magnetic member used to transfer magnetically a drivable force of said motor on said magnetic impeller.
 21. The liquid pump as described in claim 20, wherein said motor is electrifiable, and said magnetic impeller and said magnetic member are not electrifiable.
 22. The liquid pump as described in claim 20, wherein said magnetic member is a permanent magnet and said magnetic impeller has a permanent magnet installed therein.
 23. The liquid pump as described in claim 20, wherein said magnetic member is in one of the situations consisting of being juxtaposed with said magnetic impeller and surrounding said magnetic impeller. 